Developing Critical Thinking Skills in Stratified College English Courses: Experiences of Teachers in a Large University in China

Implementing critical thinking skills in education has long been the focus of educational reforms. Collecting data from semi-structured interviews and class observations, the current study investigated the teaching techniques (the exposure of students to authentic situation or problems, opportunity for dialogue, and mentoring) on critical thinking employed by teachers of English in stratified college English courses in the context of China. Data analysis showed that the techniques could be appropriately applied to the instruction of critical thinking skills for students with various language competences, and would help develop students’ critical thinking dispositions besides language en-hancement. Such findings could shed light on the teaching techniques of critical thinking in the context of stratified college English teaching.


Introduction
The past few decades have witnessed governments' efforts worldwide to reform teaching and learning to advocate critical thinking skills (Lee, 2016). Critical Thinking (CT) involves interpretation, analysis, evaluation, inference through purposeful, self-regulatory thinking (Abrami et al., 2015). In second language teaching and learning, critical thinking can enhance learners' thinking abilities and language competence (Yang & Gamble, 2013). The exposure of students to authentic or situated problems, the opportunity for dialogue and mentoring are effective strategies for teaching CT skills and enhancing students' CT disposi- tions (Abrami et al., 2015). Authentic situations or problems engage students and stimulate them to inquire. Dialogues can provide students with opportunities of idea exchanges, and various forms of dialogue include question asking, discussion and debate. Mentoring is an interaction between instructors having abundant expertise with students lacking expertise. In spite of the popularity of CT, there is a widespread concern that educational institutions have failed to properly instill CT skills and dispositions in students.
In most Chinese engineering universities, the huge differences among learners' English language proficiency pose profound challenges for second language teaching. In response to this, stratified teaching has become the trend in college English teaching reforms in China, which involves grouping students based on different language levels and instructing them with corresponding teaching materials and strategies. Critical thinking involves an intellectually disciplined process of actively and skillfully conceptualizing, applying, analysing, synthesizing and/or evaluating information gathered, and in order to accomplish these critical thinking actions, good language proficiency is crucial (Paul, 2004). Studies on critical thinking development in second language teaching and learning mainly involve teachers' cognitive beliefs, reflective argumentation and academic discourse socialization (Ma & Liu, 2018). Despite the plethora of research on the teaching of critical thinking skills in college English courses, to our knowledge, few studies have focused on the teaching in stratified college English programs, especially in large-scale engineering universities in Mainland China, where students are equipped with varying levels of language proficiency before college entrance.

Research Design
This study is based on the stratified college English programme in an engineering university in western China. According to the scores of the English placement test, all first-year students are grouped into three language proficiency levels for teaching purposes prior to their college English study. Level A stands for the advanced, level B the intermediate, and Level C the fundamental. Semi-structured interviews were conducted for six teachers, with two teachers for each level, and their years of teaching range from nine to 17 years. All of them have rich teaching experiences for at least nine years in critical thinking before stratified college English programme, since critical thinking abilities have been one of the essential objectives in this university's College English programme. Moreover, these teachers have done some research in critical thinking due to their interest and college requirements in teaching critical thinking skills. During the interviews, the six teachers recalled their teaching techniques in cultivating students' critical thinking and shared their views on students' development of critical thinking dispositions. Besides, the researcher observed the six teachers' classes for data triangulation. For the whole semester, 18 class observations were conducted at the beginning, the middle and end of the semester. The interview data were audio-recorded, transcribed and analyzed with a typical method of qualitative content analysis.

Findings and Discussion
The results suggest that based on students' varying levels of language proficiency, teachers from the three levels implement different critical thinking techniques during the process of college English teaching. While in Level A language classrooms, teachers give priority to the use of exposure to authentic problems, teachers from Level B and Level C prioritize opportunity for dialogue and mentoring respectively, although they may employ other methods in accordance with the adjustment of students' linguistic proficiency. Proper choice of these strategies at certain linguistic level can ensure both the smooth and effectiveness of cultivation of critical thinking abilities and dispositions.

Level A (Advanced) Students
For advanced-level students, compared with the other two strategies, the exposure of students to authentic or situated problems can to a large extent improve students' CT thinking skills and dispositions.  When confronted with a real problem, students at advanced level are usually curious and excited, and real problems and situation seem like hooks. They are fully engaged in analysing the problems and finding out solutions to them. (Interviewee 1)  Under teachers' instruction, most students are able to figure out the authentic problem, logically analyse it, and create the resolutions for it. In the whole process, with a focus on authenticity, the students are gradually becoming more confident in making inference, identifying the presupposition and creating their own opinions. (Interviewee 2) In class observations, researchers found that posing authentic problems can enhance students' abilities in identifying, analyzing, and creating solutions to problems independently and comprehensively. At the final stage of class observation, with the increase in their CT skills, students are more likely to be orderly in complicated problems, persistent in quest of truth, and flexible-minded.

Level B (Intermediate) Students
As far as those intermediate students are concerned, opportunity for dialogue includes ones between teachers and students and those between students and students. In comparison with mentoring and exposing students to authentic problems, the dialogues can serve as a prior teaching method for CT development.  For some students in this level, an authentic problem at the very beginning may make them perplexed, frustrated. They have no idea on how to start with it, but a series of questions can give relatively accurate direction and instruction in leading students to analyse questions, and the discussion among students can help them clarify the concepts, evaluate the resources of evidence, reason logically and create what they finally present. (Interviewee 3)  As a form of dialogue, debates require students to identify others' premises, arguments, evaluate the evidences and counter arguments, providing them with the potential to exchange ideas and regulate their thinking. (Interviewee 4) Opportunities for dialogue can provide students with appropriate guidance in analyzing and creating solutions to problems. At the end of the semester, the researcher noticed that students are becoming more confident, honest in facing their own biases, fair-minded with the improvement of higher-level thinking abilities and language proficiency.

Level C (Fundamental) Students
For those fundamental-level students, mentoring are considerably essential.  A real problem makes these students frustrated, for they don't know how to start. Moreover, question asking sometimes end in no response. They need full support in understanding problems, analyzing the causes and effects and looking for possible solutions. Their language proficiencies may hinder the cultivation of critical thinking; therefore, individualized mentoring in complicated language problems are initially needed for their comprehension, and then some higher-level thinking practices can be implemented. (Interviewee 5)  An authentic situation and questioning in depth at first make me feel I could not communicate with them well. They need more individual support. According to my prior experiences, I should be more patient with students in this level, since they have more difficulties in the low-level thinking. (Interviewee 6) Since these students' language competence and skills of identification, analysis and evaluation are limited, teachers' mentoring can help them improve their comprehension and skills application. Gradually, analyzing, inferring and evaluating can be instructed step by step with teachers' full support and patience. At the final stage of the semester, these students are becoming well-informed, cooperative and open-minded with the improvement of their language proficiency.

Conclusion
Proper and tailored implementation of the three strategies can contribute to the improvement of students' critical thinking skills and dispositions, and each has its own merits for a group of students with particular language proficiency level.
The appropriate implementation of these strategies can greatly reduce obstacles in classroom instruction and prove to be effective in students' critical thinking development.

Funding
This study was supported by the Teaching Reform Project of 0003-300103301301 of Chang'an University.